A vehicle generally has several air vents located at the dashboard so as to send air into the interior of the vehicle. The air quality of big cities is so bad that the drivers usually close the windows of their vehicles while driving so as to reduce the bad air entering into the vehicles. A simple filtering member such as a netted plate may be used to roughly filter the air coming from the air vents, it is not satisfied for the passengers in the vehicles because there are varieties types of germs in the air and are harmful to the passengers' health.